diff options
| author | Mark Brown <broonie@opensource.wolfsonmicro.com> | 2011-03-17 21:42:28 +0000 |
|---|---|---|
| committer | Samuel Ortiz <sameo@linux.intel.com> | 2011-03-23 10:42:10 +0100 |
| commit | 334e9ab8f9bb90ddf1eff0b07609961a628064b6 (patch) | |
| tree | 662945d7aed6adb546ed3915186e86b2f56b3cad /drivers | |
| parent | 4c4d887822070410e3be519e1a4ff933fb899ba8 (diff) | |
mfd: Avoid copying data in WM8994 I2C write
As well as providing a trivial performance optimisation this also avoids
allocating a copy of the message on the stack which is beneficial when
doing large transfers.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/mfd/wm8994-core.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/drivers/mfd/wm8994-core.c b/drivers/mfd/wm8994-core.c index 749c31d29b0..ce93796e7f5 100644 --- a/drivers/mfd/wm8994-core.c +++ b/drivers/mfd/wm8994-core.c @@ -580,25 +580,29 @@ static int wm8994_i2c_read_device(struct wm8994 *wm8994, unsigned short reg, return 0; } -/* Currently we allocate the write buffer on the stack; this is OK for - * small writes - if we need to do large writes this will need to be - * revised. - */ static int wm8994_i2c_write_device(struct wm8994 *wm8994, unsigned short reg, int bytes, void *src) { struct i2c_client *i2c = wm8994->control_data; - unsigned char msg[bytes + 2]; + struct i2c_msg xfer[2]; int ret; reg = cpu_to_be16(reg); - memcpy(&msg[0], ®, 2); - memcpy(&msg[2], src, bytes); - ret = i2c_master_send(i2c, msg, bytes + 2); + xfer[0].addr = i2c->addr; + xfer[0].flags = 0; + xfer[0].len = 2; + xfer[0].buf = (char *)® + + xfer[1].addr = i2c->addr; + xfer[1].flags = I2C_M_NOSTART; + xfer[1].len = bytes; + xfer[1].buf = (char *)src; + + ret = i2c_transfer(i2c->adapter, xfer, 2); if (ret < 0) return ret; - if (ret < bytes + 2) + if (ret != 2) return -EIO; return 0; |